Most electronic calipers, dividers, and the like that are currently in use provide measurements only in conventional length or angle units such as inches, millimeters, degrees or radians. Furthermore, devices that provide such measurements, particularly in the case of commercially available electronic calipers, have become near-commodities. That is, the user-controlled functions provided, the number and spacing of the buttons provided to activate the functions, and the dimensions of the electronic housing and the LCD display portion, and the like, have settled into a narrow range of configurations that provide the manufacturability, economy, functionality, and ergonomic factors that are expected or required by a majority of manufacturers and users of electronic calipers. As such, manufacturers and users are reluctant to accept design variations which increase the functional complexity, increase the number of buttons or decrease their ergonomic spacing, increase the ergonomic dimensions of the electronic housing, or decrease the ergonomic visibility of LCD display elements, etc., even to a moderate extent.
Previously proposed methods for adding additional measurement functions to electronic calipers are generally not acceptable according to the aforementioned acceptance factors. For example, U.S. Pat. No. 6,223,136 to Geiger discloses a method wherein a scaling function is performed in one of two ways: numerical input or a calculated scaling factor. The numerical input is for cases where the drawings, model, or item to be measured is of a known scale. The user inputs that scale. Further measurements are then multiplied by this scale factor and displayed. The calculated scaling factor is for cases in which the user is uncertain of the scale, but has a reference dimension. In this case, the user measures the reference dimension, then inputs the value corresponding to the actual dimension of the object. The calculation module then calculates the scale factor and scales further measurements by the scale factor. It is suggested in the '136 Patent that an increment button, a decrement button, and a enter button are provided to allow the user to access and use the scaling, nominal value, basic geometric and complex geometric functions of the invention. However, such buttons are not conventionally provided on electronic calipers, and their addition and use would necessarily violate the acceptance criteria outlined above, as would the alternatives suggested in the '136 Patent.
U.S. Pat. No. 6,497,051 to Poole discloses a method for scaling a measurement wherein the user is able to select a scale by depressing a scale button. This feature is useful when the measurement to be taken is printed on a sheet drawn in a particular scale. In that case, the user uses the scale button to select the same scale used by the printout. When the measurement ends (the elements positioned to define the measurement distance) of the measuring device are placed on the printout to measure a distance, the CPU will automatically compensate for the scale and display an unscaled measurement. For example, if an MRI image of a person is printed in centimeters and uses a scale of one to four, the device can be set for taking measurements in centimeters and a scale of one to four. If a measurement of the size of an organ is taken where the measurement ends are spaced two centimeters apart on the MRI image, the CPU will automatically calculate the actual distance and display a measurement of eight centimeters on the display. The user is also able to calibrate the device to a known distance by separating the measurement ends to a known distance and the known distance is entered into the CPU by sending a calibration signal to the CPU. This is preferably accomplished by placing the measurement ends against a legend and pressing the calibration button. This will calibrate the measurement device to read precisely a calibrated distance (provided that the calibration operation using the calibration switch is properly coordinated with the scale setting operation using the scale switch). However, a scale switch is not conventionally provided on electronic calipers, nor is the ability to display the value of a scale currently in effect (without which, the current scale might easily be overlooked or mistaken), nor is it necessary to coordinate a calibration operation using a calibration switch with a scale setting operation using a scale switch. Thus, the addition and use of any such elements would necessarily violate the acceptance criteria outlined above, as would the alternatives suggested in the '051 Patent.
Nevertheless, the addition of a scaling-like measurement capability to an electronic caliper, or the like, would be useful. Thus, a configuration of an electronic caliper, or the like, that operates to provide a scaling-like measurement capability while generally satisfying the acceptance factors outlined above would be desirable.